The NAACP says the practice is disenfranchising thousands.

Three counties in North Carolina are canceling the voter registration of thousands of eligible residents— most of them African-American Democrats — just days before the 2016 election. On Monday, the North Carolina conference of the National Association for the Advancement of Colored People (NAACP) sued the state and demanded an immediate stop to the practice, which they dubbed “a coordinated effort right out of the GOP playbook to suppress the black vote in the state.”

The lawsuit charges that Beaufort, Moore, and Cumberland counties are challenging voters’ eligibility with no other evidence than a single piece of mail that was sent to their home and bounced back as undelivered. Many of those challenged and flagged for purging, like James Edward Arthur Sr., have moved within the same county and remain legally allowed to vote. Others still live at their original registration address and fell victim to a simple postal-service error.

Arthur, who is African American and lives in a nursing home, grew up in Beaufort County and has voted in at least 14 elections. He testified that he did not receive any notice from the state or the county that his voter registration had been challenged or that he would be required to attend a hearing to keep his right to vote.

“If I knew my right to vote was in jeopardy, I would do whatever I could to protect it,” he said. “I want and plan to vote in the upcoming election, but I am concerned that since my registration has been canceled I will not be able to cast a ballot or it will not be counted.”

“If I knew my right to vote was in jeopardy, I would do whatever I could to protect it.”

The lawsuit says North Carolina is violating the National Voter Registration Act, which bans the systemic removal of voters from the rolls in the final 90 days before an election. State officials have defended the practice, claiming that the challenges have been brought individually against thousands of people rather than in a systemic manner.

But the NAACP is also accusing Republicans of conducting a coordinated mailing campaign in the first place in order to challenge the voting eligibility of thousands of people who don’t receive the mailing. Shane Hubers, a Republican who ran for local office last year, challenged the registration of dozens of voters — the majority of them Democrats — in Beaufort County. In Cumberland County, a single individual used returned mail to challenge the registrations of 3,951 voters. In Moore County, N. Carol Wheeldon, the secretary of the local Republican Party, challenged approximately 400 registered voters.

Penda Hair, the lead attorney for the NAACP in the lawsuit, said while she cannot yet prove a conspiracy, “We know that in two of the counties, the people who brought the challenges had connections to the local Republican Party. We also know that the pattern of these challenges is very similar across the the counties.”

In Moore County, Hair added, “the return address of a right-wing group called the Voter Integrity Project appeared on the piece of mail that was used to challenge voters.”

“This is a very pernicious treatment of voters,” she said.

The lawsuit also notes that a disproportionate number of those challenged are black. For instance, African Americans make up only 25.9 percent of the population in Beaufort County, but account for more than 65 percent of the voter eligibility challenges.

“We are seeing the worst attempts of voter suppression here in North Carolina that we’ve seen since the days of Jim Crow,” Rev. Dr. William Barber, the president of the state NAACP, told reporter on Monday. “The Tar Heel state is ground zero in the intentional, surgical efforts to suppress the voice of voters. These attempts are a direct affront to our Constitution.”

The NAACP is demanding the state put all voters challenged since 2012 using this process back on the rolls immediately, notify them that they have been reinstated, and allow them to cast regular ballots early or on Election Day. They are requesting an emergency hearing this week to decide the case.

These new charges come just days after a federal court found the state violating the National Voter Registration Act in another manner: by failing to add tens of thousands of voters to the rolls who registered at a DMV over the past few years. On Thursday, U.S. District Judge Loretta Biggs ordered the state to allow these voters to cast provisional ballots.

On Wednesday morning, the U.S. Justice Department filed a brief in support of the NAACP lawsuit. They argue that the National Voter Registration Act “does not permit a jurisdiction to purge voters based solely on mail returned as undeliverable,” and not that “registration challenges” are one of the “manipulative devices and practices that historically had been employed to deny the vote to blacks.”

UPDATE: The federal district court sided with the NAACP late Friday afternoon, calling for an immediate halt to the purge and ordering the state to put the illegally purged voters back on the rolls. During the hearing, Judge Loretta C. Biggs called the purge “insane” and said it “sounds like something that was put together in 1901.”

“The evidence in this case demonstrates why Congress prohibited the systematic removal of the names of voters so close to an election,” she wrote in her ruling. “Denying an eligible voter her constitutional right to vote and to have that vote counted will always constitute irreparable harm.”